The investigators propose a population-based case-control study of the role of novel nutritional and genetic factors in the etiology of hip fractures in Utah residents, ages 50 years or older. They will recruit 950 women and 950 men with incident hip fractures from a random sample of all hip fractures among Utah residents during 1997-00 and an equal number of sex- and age-matched controls. The following hypotheses will be tested. 1. Low intake of protein is associated with an increased risk of hip fracture; analyses will be extended to include source and quality of protein intake and lysine intake. Covariates in analyses will include intakes of total energy, lipid, carbohydrate, calcium, and vitamin D. 2. Allelic variants of candidate gene markers associated with osteoporosis increase the risk of hip fracture. They will study genes that are involved in bone formation and remodeling, including COL1A1 and COL1A2, the genes that encode the chains of type 1 procollagen, the vitamin D receptor, osteocalcin, osteonectin, and osteopontin. The goal is to evaluate the risk of hip fracture attributable to these candidate genes within the context of a representative human population. 3. The candidate genes and nutrients mentioned above interact, additively or multiplicatively, to increase the risk of hip fracture. Individuals with high-risk alleles for osteoporosis may be more susceptible to nutritional and other environmental causes of hip fracture. A pilot study of hip fractures among Native Americans (50 cases, 100 controls) will develop appropriate methods, including dietary assessment. Fractures among Native Americans are understudied and this minority group includes subgroups with considerable variation in bone density, dietary habits, lifestyle habits, environmental exposures, and genetic traits. The investigators state that the multidisciplinary approach proposed may lead to effective public health interventions to reduce the burden of hip fractures.